Relationships between tamoxifen use, liver fat and body fat distribution in women with breast cancer.

Tamoxifen is a nonsteroidal anti-estrogenic drug used for adjuvant treatment of breast cancer and recently as a chemopreventative agent for breast cancer and, on an investigational basis, for other cancers. To date there are case reports of hypertriglyceridemia and fatty liver disease in tamoxifen users. Fatty liver is associated with visceral obesity and other components of the metabolic syndrome. Here we evaluated steatosis and adipose tissue distribution by CT scan in a cross-sectional study of 32 women on tamoxifen and 39 control women. Tamoxifen users had more visceral adipose tissue (VAT) and more liver fat than controls. This is the first study to demonstrate that fatty liver and intra-abdominal fat accumulation are common in breast cancer patients receiving tamoxifen. Prospective studies of tamoxifen should monitor metabolic changes in obese women with or without breast cancer.